Rule number six
by TwilightPony21
Summary: A dead Navy lieutenant brings Sarah MacKenzie Rabb back to NCIS. Three-shot ficlet. (It will help if you're familiar with JAG and the NCIS back-door pilot episodes.)
1. Chapter 1

**Hi, everyone! I'm both a JAG and NCIS fan, and this is my first time writing for the NCIS fandom. I was so excited to see Bud Roberts' guest appearance on the NCIS season 14 premiere, and I wish we had heard more about Harm and Mac from him.**

 **I realize that McGee was not in the NCIS back-door pilot episodes, but he seemed to know Bud and he asked about Harm and Mac, so I'm assuming he knows what happened.**

 **Since this is my first time writing some of the NCIS characters, I haven't included the two new agents yet. I hope you like this little three-shot ficlet – thanks for reading!**

* * *

"Hello? Is anybody there?"

The young Navy lieutenant calls out in a timid voice, but the only reply is the echo of his own footsteps. It's dark, and he can barely see the hallway in front of him without squinting, and he takes a deep breath to calm the heart that he's sure is going to pound right out of his chest.

Suddenly there's a loud bang behind him, and he whirls around with a gasp as the silhouette of another man emerges from the shadows.

"Well, looky here. Johnny boy actually showed up tonight."

"Ricky, I—I don't know if this is such a good idea," he stammers.

"You chickening out, Johnny? I don't like people chickening out on me."

Ricky steps into a square of dim light, and it's just enough to highlight the wicked glint in his eyes.

It makes Johnny take a step backwards.

"Ricky, I helped you once," he says. "You didn't say anything about twice."

"But Johnny," Ricky drawls in a mock whine. "I finally got a really good buyer, and he's counting on you to deliver the goods."

"No," Johnny declares defiantly. "I won't do it anymore."

"Oh, I think you will," Ricky hisses angrily. "You're in too deep now…there's no going back."

"I—I don't think so, Ricky." With shaky fingers, Johnny draws a concealed weapon from the waistband behind his back and aims it at the other man's chest.

Ricky smirks. "What are you gonna do with that, Johnny boy?"

Johnny gulps and tries to take a firmer grip on the gun. But his finger is still trembling over the trigger when a shot rings out, and he doesn't even have time to blink before Ricky slumps forward onto the ground.

"Ricky?"

Johnny falls to his knees beside the body, shaking the other man's shoulder. But there's no response, and his hand comes away sticky with blood.

"Oh, God," he whispers. "Oh, God…I didn't fire..."

He doesn't even hear the sirens approaching outside, the splintering crack of wood as the federal agents break down the doors, or the loud exclamation that follows.

"NCIS! Drop the weapon!"

* * *

"This guy gives me the creeps."

Special Agent Eleanor Bishop tilts her head slightly to study the photo of the dark-haired, scowling Navy lieutenant posted on the plasma screen.

"Well, he definitely didn't remember to say cheese," Special Agent Timothy McGee agrees. "Lieutenant Richard Carlson," he reads from the file. "Better known as Ricky. He's been arrested for drug use before, but he's never been convicted of dealing."

McGee clicks the remote and the plasma switches to the photo of the other lieutenant.

"Lieutenant Jonathan Martin," he says. "Better known as Johnny. Exemplary service record. His CO can't say enough good things about him. His parents live in Virginia, and he has one older brother, Christopher."

"So why would a successful Navy lieutenant get involved with one who's a drug dealer?" Bishop wonders. "Not to mention take a shot at him."

"Well, when we brought him in last night, he kept saying that he didn't fire the gun."

"Then who did?"

"Well, that's what we need to find out," McGee says. "But we can't question anyone until the JAG lawyer gets here."

"She's here, Agent McGee."

Bishop and McGee both spin around at the voice behind them, taking in the sight of a U.S. Marine officer standing in the middle of the bullpen. Bishop recognizes the insignia of the Judge Advocate General Corps on her uniform, and she's extremely pretty, even in Marine green, with dark brown hair and chocolate eyes.

McGee's face breaks out into a wide grin. "Mac!" he exclaims, embracing the woman in a friendly hug.

"Hi, Tim," she says with a smile.

When he steps back, McGee immediately motions to his partner. "Special Agent Eleanor Bishop, this is General Sarah MacKenzie Rabb. She's with JAG, commander of the Joint Legal Service Center Southwest."

"Nice to meet you, ma'am," Ellie says politely. She extends her hand, and the Marine grasps it firmly.

"Likewise, Agent Bishop."

"So how are you, Mac?" McGee asks.

"Good," she replies, tucking a loose strand of hair behind her ear. "A little jet lagged. I wasn't expecting to pick up a case on my layover in Washington."

"Still racking up the frequent flier miles to London?"

"As often as I can."

Bishop is puzzled by the sympathetic look that crosses McGee's face. "What's in London?" she asks innocently.

"Office of the Force Judge Advocate," comes the brisk reply from the other side of the bullpen.

Bishop and McGee know that deep, gruff voice anywhere – and apparently so does Mac.

"Special Agent Gibbs," she greets coldly without turning around.

"General MacKenzie," he mimics in the same tone. "Or is it General Rabb now?"

His gaze feels like it's boring a hole in the back of her head. Mac doesn't even flinch.

"MacKenzie is fine."

She turns to face him and they lock eyes in a way that reminds Ellie of two angry bulls about to face off. Although she usually counts on Gibbs to stare down anyone, she can't tell who is going to win this one.

Bishop leans over to McGee and whispers, "Is this a Marine thing?"

"Picked up a Navy lieutenant last night," Gibbs says, stepping around Mac to sit down at his desk. "Found him in an old warehouse kneeling next to the dead body of one of his shipmates."

"Lieutenant Richard Carlson." Mac is already familiar with the case. "He was court-martialed in London a few months back. They caught him dealing drugs, but he got off due to mishandling of evidence."

"Yeah?" Gibbs leans back in his chair, a knowing smirk playing on his face. "Force Judge Advocate probably isn't too happy about that, is he?"

Mac's eyes narrow. "No, he's not."

"Didn't think so."

There's another uncomfortable silence, and just when Bishop and McGee start to wonder if that's all Gibbs and Mac are going to say to each other, the ring of a cell phone slices through the tension in the room.

"Yeah? Gibbs."

He listens for a moment and then snaps his phone closed. "Ducky's got something. McGee, Bishop, our lieutenants." He points to the plasma. "Everything about them. MacKenzie, you're with me."


	2. Chapter 2

**Thank you all for reading and for your nice reviews! Always happy to meet new JAG and NCIS fans. I hope you like chapter 2!**

* * *

"Sarah!"

Dr. Mallard's face lights up with surprise as the Marine general walks through the door to autopsy.

"Ducky," she acknowledges him with a warm smile.

"It's been a long time since you've been on the east coast, my dear."

"I guess I'm just having too much fun soaking up that southern California sunshine," Mac teases.

"Well, it's certainly easier on the old bones than those dreadfully gloomy days in London," Ducky concurs. "In fact, even when I was a young lad there, I found that the only thing that would help take the chill off was—"

"You got something, Duck?" Gibbs interrupts impatiently.

"An absolutely delightful recipe for Yorkshire pudding," Ducky replies, although he's obviously still speaking to Mac. "In fact, I must send it to that husband of yours. He still cooks, I presume?"

Mac nods. "He does."

"Then I imagine he'll be quite fond of it," Ducky says brightly. "This particular recipe is entirely vegetarian, but it has a lovely crispy crust with an extra fluffy texture—"

"The body, Duck!" Gibbs turns his glare on the medical examiner and jerks his head in the direction of the corpse lying on the table.

"I was just getting to that, Jethro," Ducky assures him. He makes his way over to the table and pulls on a pair of gloves. "And if you'll wait just a moment, I believe we'll be able to quickly surmise the fate of our unfortunate lieutenant."

Gibbs and Mac peer curiously over his shoulder as Ducky gently probes some flaps of skin. "It seems that Lieutenant Carlson was fatally struck by a bullet, and the shooter was quite precise. It severed his carotid artery and death was nearly instantaneous."

"Lieutenant Martin says he didn't fire," Gibbs informs him.

"Well, perhaps not," Ducky replies reasonably. "But someone did."

"You got the bullet?" Gibbs asks. "Can we match it to Martin's gun?"

With a pair of forceps, Ducky carefully removes the mangled bullet from the body and deposits it in a small container.

"That, Jethro, we won't know until we get this up to Abby."

* * *

 _From the halls of Montezuma,_

 _To the shores of Tripoli,_

 _We fight our country's battles_

 _In the air, on land, and sea._

"Mac!"

Mac barely hears her name over the pulsing drumbeat of the U.S. Marines' hymn, and she doesn't even have time to suck in her breath before she's wrapped in a crushing hug by a whirlwind of black hair and a white lab coat. It's only after squeezing the Marine as tightly as she can that Abby releases her and remembers to press the mute button on the music.

"I mean...General MacKenzie Rabb, ma'am!" Abby immediately snaps to attention and raises her right hand in salute.

Mac laughs. "Oh, Abby, you don't have to call me ma'am."

"Yes, General MacKenzie Rabb, sir!"

Abby salutes again and Mac finds herself pleasantly amused by the forensic scientist.

"At ease," she says with a smile.

Gibbs doesn't look quite as amused. "Abbs, you got anything on that bullet?"

"Yes, gunnery sergeant, sir!"

"Don't call me sir."

"Yes, gunnery sergeant, ma'am!"

"Abby—"

"Gibbs," Abby protests indignantly. "We're in the presence of a highly decorated Marine general here. I'm just trying to show some respect."

"How about you show me something on that bullet?"

Abby frowns and turns back to her computer, her black pigtails swinging wildly. Her fingers fly over the keys and a number of photos pop up on the screen. Quickly, she zooms in on the diagram of the bullet and its striations.

"Well, Gunnery Sergeant Sucking-all-the-spirit-out-of-semper-fi, that bullet definitely did _not_ come from Lieutenant Martin's weapon."

"How do you know?" Gibbs asks.

"Well, first of all, the striations don't match. But there's an even better answer." Abby flashes a wide grin as she steps over to her table of evidence and picks up Lieutenant Martin's weapon. "This gun jammed."

"It jammed?" Mac echoes in confusion.

"As in, all of the bullets are completely stuck in the magazine. This weapon didn't fire because it _can't_ fire. So there's no way that Lieutenant Martin could have shot Lieutenant Carlson last night. The bullet that killed Carlson must have come from another weapon, which means there also must have been someone else firing it."

"We didn't find evidence of anyone else at the scene," Gibbs argues.

"Maybe you didn't, Gibbs," Abby says smugly, "but I did."

She pulls up another photo on screen. "Inside the weapon, in the spot where the mechanism jammed, there was a tiny fragment of skin that got caught in there. And when you have skin, you have DNA," she declares triumphantly.

Mac studies the screen intently. "But the skin isn't from Lieutenant Martin?"

"Nope," Abby replies. "It's not a one hundred percent match to Lieutenant Martin." Her eyes light up with excitement. "But it _is_ a fifty percent match."

"Fifty percent?"

Gibbs takes a step closer to the screen where the numeric result flashes in bright green.

"Only one way that two men are a fifty percent DNA match," he says.

"When they're brothers," Mac realizes.

Sharing an icy look of understanding, Gibbs quickly exits the lab with Mac close on his heels.

"And that's why we leave it to the Marines," Abby declares.

Now alone in her lab, she presses the button to unmute her music with a flourish.

 _First to fight for right and freedom_

 _And to keep our honor clean_

 _We are proud to claim the title_

 _Of United States Marines._


	3. Chapter 3

**Hi, everyone! This is the last chapter of this little ficlet, and you'll find that everything wraps up pretty quickly. But it was fun to write Mac with the NCIS characters – maybe someday we'll actually get to see her on the show. Thanks for reading!**

* * *

"So what's up between Gibbs and General MacKenzie Rabb?" Bishop asks, stepping into the room behind the interrogation room glass.

McGee raises an eyebrow. "Who said anything was up with them?"

"Oh, come on, McGee," Bishop wheedles. "You can just feel the tension between them."

She looks at McGee expectantly, and McGee decides that a shortened version of the story will save him from further questioning. "Years ago, NCIS investigated the murder of a JAG lieutenant. Gibbs was the lead investigator, and Mac was also…um, involved."

"She was the suspect?" Bishop guesses.

"No, but her husband was."

Bishop's eyes widen.

"Well, he wasn't her husband back then," McGee explains quickly, "but they were partners. You know, like you and me"—he pauses—"well, not exactly like you and me—"

"McGee, quit while you're ahead," Gibbs grumbles, entering the room and closing the door behind him.

"Uh, right, sorry, Boss."

Sheepishly, McGee and Bishop turn their attention back to Mac who is pacing the interrogation room like a caged panther. Christopher Martin sits at the table silently, his hands clasped tightly in front of him and his head bowed.

Mac opens with a direct question. "So where were you last night, Christopher?"

"At home, ma'am."

"You sure about that?"

"Where else would I be, ma'am?"

Mac finally stops her incessant pacing to face him from the other side of the table. "Well, it seems your little brother Johnny was out meeting one of his friends."

Chris scoffs. "Ricky is not a friend."

"So you know Lieutenant Carlson?"

"I know enough about him."

"And how well does Johnny know him?"

Chris shifts uncomfortably in his chair. "Johnny's been…hanging out with him for a while," he says. "But it's not his fault. He just got mixed up in the wrong crowd."

"Mixed up enough to kill one of them?"

"Johnny would never shoot anybody!" Chris exclaims loudly.

"He brought a weapon with him last night," Mac argues. "Circumstantial evidence might suggest that he intended to fire it."

"He didn't fire it."

"Because _you_ jammed it."

Chris immediately looks away at the accusation – off to the side and then up at the ceiling, anywhere but into the angry eyes of the Marine sitting across from him. "I didn't want Johnny to get in trouble," he admits quietly. "He didn't know how to get Ricky off his back, so he was going to do the only thing he could think of."

"But you didn't want to let that happen." Mac's voice is low and almost menacing now. "You were willing to take the fall for your brother, is that right? Would you kill for your brother, Christopher?"

"I told you, ma'am," Chris insists forcefully. "I didn't kill anyone, and neither did Johnny. The gun jammed."

"Johnny's gun jammed," Mac corrects. She opens the briefcase on the table and pulls out a gun wrapped in an evidence bag. "What about this one?"

Chris's eyes widen into round circles as Mac tears open the bag. She checks the clip and cocks the gun, and her finger hovers on the trigger as she raises the barrel towards the ceiling.

"Uh...Boss?" McGee says nervously from behind the glass.

"Gibbs?" Bishop has the same concern, and she takes an involuntary step back. "She's not actually going to fire that thing, is she?"

Gibbs doesn't even blink. He stares at both of them silently and takes a sip of his coffee.

* * *

He finds her sitting on a bench just outside the NCIS building, her eyes staring off into the afternoon sun and her hair blowing gently in the breeze.

He hands her a cup of strong black coffee, and Mac accepts it with a raised eyebrow.

"Can't guarantee it won't kill you," he says.

"I'm a Marine, Gibbs. I can handle your coffee."

He sits down beside her without waiting for an invitation, and he takes a sip of his own beverage, daring her to drink hers.

"You learn that interrogation technique from your husband?" he asks casually.

Mac rolls her eyes. "I learned a lot of things from my husband, Agent Gibbs."

"Yeah? Like how to get Christopher Martin to admit to the murder of Lieutenant Carlson?"

"He couldn't handle the guilt," Mac explains. "He knew Johnny was mixed up in the drug deal and the only way to get him out of it was to eliminate Ricky. It was only a matter of time before we found the actual murder weapon. And he didn't want Johnny to take the fall." Her voice dropped almost to a whisper. "So in the end, he was simply a man who wanted to protect his little brother."

Suddenly they're not talking about Christopher Martin anymore.

"It was a long time ago, Agent Gibbs," she says quietly.

"Yeah, it was." Gibbs' expression doesn't change. "That's why I got a rule."

"I hear you have several."

"Rule number six. Never say you're—"

"Sorry," Mac finishes. "It's a sign of weakness. I know that one, Gibbs."

Gibbs shrugs. "But if I didn't have that rule..."

Mac looks up in surprise.

"I might have something to say to your husband."

Mac's eyes widen and she stares at him for a long time. Finally, she nods. "I'll tell him that, Agent Gibbs."

"You do that."

And as the sun slowly sets on the Navy yard horizon, the two Marines sip their coffee in silence.


End file.
